* The oldest page is therefore the one withthe highest value of
* cur_lru_count- page_lru_count[slotno]
* The counts will eventually wrap around, butthis calculation still
* works as long as no page's age exceedsINT_MAX counts.
*----------
*/
int cur_lru_count;
/*
* latest_page_number is the page number of thecurrent end of the log;
* this is not critical data, since we use itonly to avoid swapping out
* the latest page.
*/
int latest_page_number;
} SlruSharedData;
typedef SlruSharedData *SlruShared;
下面看看初始化完" SUBTRANS Ctl"相关结构后在内存中的结构图
初始化完SUBTRANS相关结构的内存结构图
为了精简上图，把创建shmem的哈希表索引"ShmemIndex"时创建的HCTL结构删掉了，这个结构的作用是记录创建可扩展哈希表的相关信息。增加了左边灰色底的部分，描述共享内存/shmem里各变量物理布局概览，由下往上，由低地址到高地址。其中的"SUBTRANSCtl"即clog的相关结构图下面分别给出，要不上面的图太大太复杂了。
SUBTRANS相关结构图